Dynamo-electric machine



Feb. 28, 95() W, 1 OBRIEN 2,499,325

DYNAMOELECTRIC MACHINE STRUCTURE Filed Aug. 27, 1945 2 Sheets-Sheet l,4free/vir.

Patented Feb. 28, 1950 UNH-'ED STATES E NT FF IC Ef DYNAMOELECTRICMACHIN-ESTRUCTURE ApplicationAugustiZ, 1945, SeriallN. 612,984.

5.y Claimsf. (Cl. 171.-252lf l. My inventionrelates to an electricalinstrument and has particular'reference to a new coil struc-Av turewhich iinds particular utility when used with: goniom'eters and likedouble field instruments.

In goniometers, synchroscopes, power factor` meters and similarinstruments, twosets of field. coils are used with their axes disposedat right angles to each other. For these instruments, to faithfullyindicate the angular relationship loe-rtween the two coil potentialsfitis necessary that the coils be so arrangedas'to produceauniform' andundistorted magnetic` field; Prior to my invention this requirement'wasnot fullyfmet and such uniformity as was obtained was'obtained at theexpense of the eicency ofthe instrument or'at unreasonable cost.

In certain electrical systems an indicationof this accumulative anglechange--betweentwo alternating potential systems is often required.` Inthe absence of the device of'my invention, this can be accomplishedonly'through the use: of large; expensive or inaccurate-apparatus:`

It is, therefore, an object of my-vinventiontto provide an instrumentfor indicating the-accumu lative angle change between two alternatingpo.tentiai systems and which comprises-agoniomef ter coupled toanregistering*mechanism.-v

It is an additional object: of :my` invention .to provide a.-` coilstructure having; a. goniometen which includes twopairsofz identicalcoil supeportsI mounted symmetrically; and. atright angles to eachother.

It is a' still further object of, my inventionto provide. acoil:structure'of .the ftharacter.'set-forthy in' the` precedingparagraphinwhich one-fof the;k pairs of supports encircles and is=supportedfby the other pair:

It is also anobject of my invention to provide azzccil structure of thecharacter setforth in'whch the'coil supports are'formedfofinsulatingmate.` rial of' channel-shaped-l crossf sect-ion` and given arectangnlarshape'.

It' is additionally Yan' objectfoffmy: inventionzto provide astructureof thechara'cter 'describedin the preceding-paragraph iniwhicmthe: long. infy ternal dimension' of the .suppor-.tiishz substantiallyequal -to the short'externaldimension;

Other objects and" advantages of my invention' will be apparent from astudy'oi'theffollowingf` speci'cations, read in connectionwith'theiaccompanying drawings; wherein;

Fig. 1 is a perspective-'view'illustratingtnelgeneeral 'form and"appearance? of :aia registering-'genis ometerr comprising .I the-14preferredi; embodmento myrinventi'onz' Y Fig. 2.is1anend View showingtheinstrument off Fig. 1.. with. the.; dial plate .removed toilll'lsr``trate the gearing employed for.. driving1 theregise tering mechanism;

Fig. 3 is fa.-V longitudinal sectional; view. of." the instrument shownin Fig- 1;.

Fig; 4-.is a. cross sectionalyiew of..the.,coi1`fstruc;i ture used. inthe instrumentand ,illustratingpair-1Av ticularly theasymmetrical.arrangement ,ofjidenti l calr coils .which characterizes,myyinventionp Fig. 5 is, an. explodedperspective. view showing?. themanner of assemblyof. the coils and rotorof' the goniometer portion ofthe instrumentnand Fig.. ,6 isi,y a .perspectiveviewl illustrating amodified.. form.- of. rotor. Which. may. be.. used" in place: of therotorshown ,in Figssljhrough 5.;

Referring, to. the. drawings, I' have illstrated as'. the. preferredembodimentl off my. invention .at registering goniometer. designed' forush panel mounting.. The devicegas.. illustratecllcomprisesE amain case:or housing.. I'. to. which is'attaehedfby any.y suitable.. means. a..lmounting iiange 2'; tlie iiange 2 being,` drilled .as indicated' at. 3'to...permity the devicest'o.be;mountedon a supporting panel;v

Withinthelflnge 3 there. is mounteda circular dial plate Awhichisggraduated' around its p eriplr-l ery-as by a-,pluralit'yof"graduations,5 etched;` or: suitably inscrbedlin or upon thexdialvplate' 4E Thecircle comprisingthe.graduations 5. may Ue' dividedjntc anydesirednumber of'parts; Tl'iel graduations showns in' Fig. 1 compriseone` liun'-` dredldivisions for. af1ll'circ1e, this formof gradi#uatiombeing select'edfor convenience;

The.. scale. comprising the graduations 5f is traversed. by a. pointer6; which is mounted upon a., centrally located" and' axially extending"goniometer shaft'. l; Above. the shaft 1j there are. pro'-` vided.registeringdia1s. 8,' Siland. l0, ,each or`*tl1esev dials being,.bypreferenca ldvidedtinto` ten equal divisions and being4 arranged to..be traversed by indicating handsd l; .I Land-1.3. The'hands.|.1|-l 3`aremounted, respectively, uponshafts. |l`,',|'5.andr Hix'Iheseshaftsaraconnectedto each other-and to. the: goniometer shaft.. T.by.- gearing. to bade-.- scribed hereinafter andarrangedto..prox/idealen to; one.-l drive; ratio,H betweenv the shafts:7" I I;

between; the...shafts. I.4` and. l5. and. between: tht' shafts, |15 andlr6., Thus-fthe. dial, llmay bananisidered. as; indicating the'. 1003s,the dia/1.9.l frsindicating-r the-,l0.s,. the, dial. 8:1 as indicating.-the 15s? and: the', diahv comprising,v the. graduations 5 Ither-.decimalipartslofzarunitgoneif revolution l the@ pointencorrespondingdentrgraxiilatonsz.

thei-r thee pointeir: l If between; two'aces.-

The gearing which is employed is illustrated in Figs. 2 and 3. As isshown in Fig. 3, the goniometer shaft 'l is journaled in the dial plate4 and also in a supporting plate I1. The dial plate Il and supportingplate I1 are mounted within the tubular housing I and held in the properspaced relation by a spacing sleeve IS which is interposed between thetwo plates. The assembly is retained within the housing I by means of anoverhanging portion I9 of the flange 2.

The gearing above mentioned is interposed between the dial plate 4 andthe supporting plate I1 and comprises a pinion 25 secured to thegoniometer shaft 1 and meshing with a driven gear 2l secured to thepointer shaft I4. Upon the pointer shaft I4 there is mounted a pinion 22which meshes with a driven gear .23 mounted upon the shaft l5. Similarlya pinion 24 mountedl upon the shaft I5 meshes with a driven gear 25mounted upon the shaft I5 which drives the pointer i3. The drive ratioAbetween each ofthe pinions and their respective driven gears is madeprecisely ten to one. i

The goniometer shaft 1 is extended through the supporting plate I1 andcarries a driving element 2G illustrated in Figs. 3, 4 and 5 ascomprising a permanent magnet. The inboard end of the shaft 1 ispreferably supported by a jeweled pivot consisting of a conical end 21formed on the shaft 1 and received within a suitable depression formedin a jewel 23 which may comprise a sapphire or other suitable instrumentjewel.

f The jewel 28 is suitably mounted within a carrier plug 29 which may besecured as by means of threads 3U to an end cap 3| which is in turnfastened to the housing I as by means of threads 32 and which servesalso as an end closure for the housing. The end cap 3I serves also tolock the assembly rigidly within the housing i, and to. this end spacersleeves 33 and 34 are placed within the housing I adjacent thesupporting plate I1 and the end cap 3|, respectively. These sleeves bearagainst the plate I1 and end cap 3I and also against opposite faces of agoniometer field structure identied generally in Fig. 3 by the referencecharacter 35. vThe eld structure which is described hereinafter isarranged to impart to the rotor 26 an angular rotation which is exactlyequal to the change in phase angle between two alternating potentialsystems connected to the field coils of the instrument. The extent ofthis rotation is indicated by the pointer 6 on the dial 5 and if itamounts to more than one full revolution, the accumulative total of theangular changes is registered and indicated by theV dials 8, 9 and I.

The field structure 35 is preferably constructed as shown in Figs. 4 and5 and comprises a main frame 35, two pair of coil supports 31a, 31h and38a, 38D, and field coils 39, 4l), 4l and 42 wound upon the supports31a-38h. The main frame 36 is formed as a rectangular block throughwhich is axially extended a cylindrical bore 43 for re' ceiving therotor 26.

j AFrom the midportion of the four side faces ofthe rectangular blockthere extend four rai dially disposed ribs 44, 45, and 41. The ribs 45and 41 are located diametrically opposite to each other as are the ribs44 and 45. The length of .the ribsl is adjusted so that the overallwidth from the outside edge of the rib 45 to the "outside edge ofthe rib41 and the corresponding measure;- frlent across ribs 44 and 46 'airefrna'de substan-'- tially equal to the inside diameteroftlre'cylini' 4drical housing I so that the main frame 35 may be inserted within thehousing in the manner illustrated in Fig. S and held by the ribs lll- 41centrally within the housing.

Each of the coil supports 31a-38b is made identical and is given achannel or U-shaped cross section dened by a laterally or horizontallyextending web portion 48 flanked on either side by outwardly extendinganges 49 and 5B. This U-shape defines a channel within which the coilwindings 39-42 may be wound.

The dimensions of the main frame 35 and the coil supports 31a- 38h beara unique relation to each other which permits their assembly in a mannerto be described hereinafter which in turn provides for a uniform andhighly efficient magnetic field. To this end the long inside dimension(see dimension line 5l on coil support 38a of Fig. 5) is made equal tothe short outside dimension of the coil support (see dimension line 52of support 31a, Fig. 5) Similarly, the axial length of the main frame 35(dimension line 53) is made equal to the short inside dimension of thecoil support (see dimension line 54, support 31h, Fig. 5). Also, thelong radial width of the main frame 35 represented by the dimension line55 of Fig. 5 is made substantially equal to the long inside dimension ofthe coil supports 31a- 38b. Similarly the short radial width of the mainframe 35 represented by the dimension line 56 is made equal to thesmaller inside dimension 54 of the coil supports 31a-38h. Finally, theoutside width of each of the coil supports 31a- 38h (see dimension line51, coil support 31h, Fig. 5) is made equal to one-half the differencebetween the narrower main frame width 56 and the width of the ribs 44and 46 so that the space along the end faces of the main frame 36 onopposite sides of the ribs 44 and 45 are exactly equal to the width 51of the supports 31a3b.

With the dimensions selected as above de scribed. the device may beassembled as follows: First, the coils 39-42 are wound in the coilsupports 31a-38h. The rotor 26 is then placed within the bore 43. 38hare then moved toward each other as viewed in Fig. 5 to encircle themain frame 35 on opposite sides of the ribs 44 and 45, as is shown inFig. 4. The coils 31a and 31h are then turned with their long dimensionvertically as distinguished from the horizontal disposition of thelength of the supports 38a and 38h and are then moved toward each otheras viewed in Fig. 5 to encircle the main frame 35 on opposite sides of fthe ribs 45 and 41 and to encircle also the previously installedsupports 33a and 38h.

The final positions of the supports 31a and 31h are shown in Fig. 4.Note that when the coil supports are installed as described, the openends of the cylinder 43 are closed except for square holes at each endhaving side dimensions equal to the width of the ribs 45 and 41. Throughthese squareholes the goniometer shaft 1 extends. The width. of the ribs45 and 41 is adjusted to space the centres of the coils of each pairapart a distance substantially equal to the means effective radius ofthe coil. This dimension is not critical and considerable variation fromthe desired spacing may be tolerated.

Note also that the field coils are identical, that they are mounted atexactly right angles to each other, and that they are spaced equallyfrom the axis of rotation of the goniometer rotor 25.

Furthermore', the coil supports 31a and'31b over-.1,l lying the supports38a and 3813 serveto -loclrtlie- The coil supports 38a, and' y nieuwe@latter securelyN piacer that@ it@ is impossible for them?- to move fromtheirrinitially installed; positions` The outer coilisupports 31a anda3=1b ai-esecuredin their'properf'locations by any; suitablemeansias, forexample, by means of aniadhesive" or-cement interposedibetwefemtheflangesfll and 50'Fa'ndfthe ribs 45 and 47a, v y

The field: structure just `describen is preferablyn'ia'deofa'non-magnetic materiallsq as tdfprevent any distortion oftheveld produced: by the'inter'.; actionof theiour. eld coils. Il. liavefouifdlth'at the'struc'tui'e -justdescribedl caribeY readily imaiiuefactured fromA a thermo-settingtsynthetic; re'sih such.asthef-phenol-formaldehyde:iiisulatin'gi ma'.- terials by a diecastingor molding process. With this process theidinensinsin'iayfbe'f' heldclosely to the required tolerancesand. the device may. be;4 manufacturedin large quantities at love;J cost; Because of the excellent dielectricproperties of these materials, the electrical insulation of the windingsone from the other is made very simple. For low frequency work wheredamping of the rotating element is desirable, the entire main frame 36may be made of copper or aluminm.

The permanent magnet rotor 26 previously referred to is preferablyformed of a permanent magnet material having high retentivity, apreference being expressed for the aluminum-nickelcolbalt alloys such asthe one marketed under the tradename Alnico.

The cylindrical magnet is transversely magnetized; that is, the portion58 lying on one side of a longitudinal diametrical plane represented bythe dotted line 59 in Fig. 5 is given a magnetic polaritv opposite tothat given to the remaining half` 60.

In certain types of instruments of the general class to which thisinvention relates, it is desirable to use a rotating coil as thegoniometer rotor in place of the permanent magnet rotor 26. In Fig. 6 Ihave illustrated a coil supporting structure which may be used for suchpurpose. The structure shown in Fig. 6 is preferably molded fromBakelite or other suitable thermo-setting phenolic resin and is giventhe general form of a rectangular solid.

The end faces of the block are bored as indicated at 6| and 62 toreceive the goniometer shaft I and the diagonal transverse dimension ofthe block is made somewhat less than the diameter of the cylindricalbore 43 so that the block may freelyA rotate within the bore. Laterallythrough the block there is cut a rectangular window 63. The side facesof this window may be recessed as indicated at 64. The coil which is tobe mounted within the coil support is. by preference, prefabricated,slipped intolthe' recess 64 and secured therein by any suitable means.

From the foregoing it will be observed that I have provided anindicating and registering goniometer which is characterized by theemployment of a registering dial for totalizing and indicating thenumber of full revolutions made by the goniometer shafts. Furthermore,the instrument of my invention employs a unique 1 coil structurecomprising the main frame 36 and the two pairs of coil supports 31a.,31h and 38a, 38h.

Attention is directed to the fact that with the coil arrangementdescribed, the coil supports are made identical and are so mounted uponthe main frame 36 as to bring them as close to the axis of theinstrument as thev diameter of the goniometer shaft 1 will permit.

inscrit willbeifnbted thatitneiassembled strinset tuif'e-` is'completelyJ symmetrical s'o thatthere? isi produced afcompletely"uniform and' undl'sto'rted mag-n'etic''-ield."l

While-'l :rv have shown an'd descriedtrie pre1 ferrea embodiment`l offmy invention; Ifdo' not dessire" to" be limited" tdanyof"the;details"of'cn-4 strctiorishown or 'described'i'herein 1. In an'electrical goniorneterj a field'y struc-- ture*compri'sing:` a` mainframe" dning an"A axisofs rotation; and two pair` of Held: coilsonsaidframe; all of*Y said; coils being'-` identical, the* coilsi o'f:Aeach pair being mounted coaxiallyandithet coils of one4 pairibeinigdisposed at" righty aligl's` toi'tlie coils ofthe other" pair, saidcoils being4 ailE spacedffrcm saidf'axis of rotation equal disin tancessubstantially less than one-half themeafri" diamete'rof said coils;`

2. In an electrical goniometer. including a rotating elementmo'unt'ed'onV a small` diameter rot'tlngf sliZ-ftyaeld'strilctieicbinprislg I a. niln frame defining an axis of rotation'coiricident' with said shaft; and two pair of field coils on said frame,all of said coils being identical, the coils of each pair being mountedon opposite sides of said axis of rotation and in parallel planesdisposed parallel to said axis, the coils of each pair being spacedapart a distance substantially equal to the mean eiective radius of saidcoils, and the coils of one pair being mounted at right angles to thecoils of the other pair.

3. In an electrical goniometer including a r0- tating element mounted ona small diameter rotating shaft, a field structure comprising: a mainframe defining an axis of rotation coincident with said shaft; and twopair of eld coils on said frame, all of said coils being identical, thecoils of each pair being mounted on opposite sides of said axis ofrotation and in parallel planes disposed parallel to said axis, thecoils of each pair being spaced apart a distance substantially equal tothe mean effective radius of said coils, and the coils of one pair beingmounted at right angles to the coils of the other pair, the coils of oneof said pairs being wound about and encircling the coils of the otherpair.

4. In an electrical goniometer including a rotating element mounted on asmall diameter rotating shaft, a eld structure comprising: a main framedefining an axis of rotation coincident with said shaft; two pair ofcoil supports on said frame, said supports being identical and formed ofinsulating material having a channelshaped cross section defining a wirereceiving space, said supports being rectangular in shape with theinside length substantially equal to the outside width, the supports ofeach pair .being mounted on opposite sides of said axis of rotation andin parallel planes disposed parallel to said axis, the centers of thesupports of each pair being spaced apart a distance substantially equalto the mean effective radius of said supports, and the supports of onepair being mounted at right angles to the supports of the other pair;and a solenoid coil wound upon each of said supports.

5. In an electrical goniometer including a rotating element mounted on asmall diameter rotating shaft. a field structure comprising: A mainframe having substantially the form of a rectangular parallelepiped anddeiining an axis of rotation coincident with said shaft; two pair ofcoil supports on said frame, said supports bef--v ing identical andformedof insulating material having a channel-shaped crosssectiondefining a Wire receiving space, said supports being rec-l tangular inshape with the inside length substantially equal to the outside Width,said main frame having a height measured parallel to said axis and deptheach substantially equal to the inside Width of said supports and havinga breadth substantially equal to the inside length of said supports, thesupports of each pair being mounted on opposite sides of said axis ofrotation and in parallel planes disposed parallel to said axis, thecenters of the supports of each pair being spaced apart a distancesubstantially equal to the mean eieotive radius of said supports, andthe supports of one pair being mounted at right angles to the supportsof the other pair; and a solenoid coil Wound upon each of said supports.v

WILLIAM J. OBRIEN.

REFERENCES CITED l The following references are of record in the file ofthis patent:

Number Number 8, Y UNITED STATES, PATENTS Name Date Steinmetz Aug. 8,1899 Evershed Jan. 21, 1908 `Lee Oct. 13, 1914 Hodde et al Mar. 26, 1918Persons Aug. 15, 1933 Kollsrnan et al Apr. 29, 1941 Eaton Mar. 31, 1942Somers Aug. 22, 1944 Hiller .Aug. 14, 1945 Goodall Oct. 8, 1946 LWarshaw Apr. 29, 1947 Smith Jan. 4, 1949 FOREIGN PATENTS Country Date fl Germany Mar. 8, 1932

